Recording rewritable time related information on a label

ABSTRACT

A method of recording rewritable time related information on a label, includes the steps of providing an electrically rewritable label associated with an article which includes a plurality of rewritable segments, each such segment having a layer including a material which is effective in at least first and second optical states so that the time related information can be written, rewritten and viewed, wherein such time related information relates to usage or potential usage of the article or a device associated with the article and such time related information can be electrically changed by providing appropriate electrical fields to the material, and electrically addressing selected segments to write or rewrite appropriate time related information.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] Reference is made to commonly-assigned U.S. patent applicationSer. No. ______ filed concurrently herewith, entitled “A RewritableDisplay Having a Dielectric Spacing Layer” by Stanley W. Stephenson, thedisclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to recording rewritable timerelated information on a label which can be provided on an article.

BACKGROUND OF THE INVENTION

[0003] Audio-visual (A/V) recordings, such as movies, can be stored on avariety of media. Currently, such recordings are stored on videocassette record (VCR) tapes or Digital Video Disk (DVD) optical storagedisks. Such media is subject to damage and is typically stored in astorage case. Agencies have been developed to provide rental of suchrecordings on either type of storage media. A renter pays an agency toposses a given recording for a given time period. Agencies rent storagecassettes for variable amounts of time at different prices. Suchagencies also rent computer games at a price for a given time period.Financial penalties are be assessed if the media cassette is notreturned by a certain return time. It would be useful to display thatreturn time on the storage cassette to prevent late fees.

[0004] Currently, a paper receipt is typically provided as a record ofthe return time to a customer for a given cassette. Alternatively, anadhesive label with the return time could be applied to the case. U.S.Pat. No. 5,040,296 discloses and adhesive label for a VCR cassettehaving a permanent set of indicia printed and covered with a surfacethat permits erasable marking. An alternative method is shown in U.S.Pat. No. 5,727,818 wherein indicia formed by pressure from a pointed tipare erased by lifting the protective sheet.

[0005] An electronic label is disclosed in U.S. Pat. No. 6,065,701. Anadhesive label can be applied to a VCR cassette. The label contains anantenna and integrated circuit that permits the exchange of data betweenthe circuit on the label. The unit can store and transmit data but doesnot permit a renter to visually determine a return date.

[0006] Fabrication of flexible, electronically written display sheetsare disclosed in U.S. Pat. No. 4,435,047. A first sheet has transparentITO conductive areas and a second sheet has electrically conductive inksprinted on display areas. The sheets can be glass, but in practice havebeen formed of Mylar polyester. A dispersion of liquid crystal materialin a binder is coated on the first sheet, and the second sheet is bondedto the liquid crystal material. Electrical potential applied to opposingconductive areas operate on the liquid crystal material to exposedisplay areas. The display uses nematic liquid crystal material whichceases to present an image when de-energized.

[0007] U.S. Pat. No. 5,437,811 discloses a light-modulating cell havinga polymer dispersed chiral nematic liquid crystal. The chiral nematicliquid crystal has the property of being driven between a planar statereflecting a specific visible wavelength of light and a light scatteringfocal-conic state. The structure has the capacity of maintaining one ofthe given states in the absence of an electric field.

[0008] It is desirable to have time related information related to anarticle or device which will be used by a user. For example, a cassettemedia or some rental article. Typically what happens is the renter willtell the renter verbally or provide a written paper or receipt whichwill specify the period of rental. This is inefficient and unreliablefor the renter, who will be confused about the time period of rental.

SUMMARY OF THE INVENTION

[0009] It is an object of this invention to provide a method forpermitting a user to visually inspect an article to determine therelated time rental information.

[0010] It is another object of the invention to make use of aninexpensive electronically written label display.

[0011] These objects are achieved by a method of recording rewritabletime related information on a label which can be provided on an article,comprising the steps of:

[0012] a) providing an electrically rewritable label which includes aplurality of rewritable segments, each such segment having a layerincluding a material which is effective in at least first and secondoptical states so that the time related information can be written,rewritten and viewed, wherein such time related information relates tousage or potential usage of the article or a device associated with thearticle and such time related information can be electrically changed byproviding appropriate electrical fields to the material;

[0013] b) providing the label to be associated with the article; and

[0014] c) electrically addressing selected segments to write or rewriteappropriate time related information.

[0015] It is a feature of the present invention that it is particularlysuitable for use with rental devices such as media cassettes devices orother rental devices. The present invention is useful for users in thatit provides an electronic label which provides a user with timeinformation (such as return time) concerning the rental device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a front view of a display in accordance with the presentinvention;

[0017]FIG. 2 is a sectional view of the display of FIG. 1;

[0018]FIG. 3 is a sectional view of a domain of cholesteric liquidcrystal in a polymer matrix;

[0019]FIG. 4 is a view of the optical characteristics of cholestericliquid crystal in each of two stable states;

[0020]FIG. 5A is a top view of a display having a light modulating layercoated over a first transparent conductor;

[0021]FIG. 5B is a top view of the display of FIG. 4A with a portion ofthe light modulating layer removed to show the first transparentconductor;

[0022]FIG. 5C is a top view of the display of FIG. 4B having a printeddielectric layer with unprinted image areas;

[0023]FIG. 5D is a top view of the display of FIG. 4C having secondconductors printed over the dielectric layer;

[0024]FIG. 5E is a top view of the display of FIG. 4D with contactsattached to each second conductor;

[0025]FIG. 5F is a top view of the display of FIG. 4E and having anapplied adhesive coating;

[0026]FIG. 6A is a sectional view of a contact connecting to a secondconductor forming an image;

[0027]FIG. 6B is a sectional view of a contact connecting to a secondconductor providing ground potential to the first transparent conductor;

[0028]FIG. 7 is an electrical schematic of circuitry to write andrewrite time related information to display 10; and

[0029]FIG. 8 is an electrical waveform used to erase and rewrite todisplay 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0030]FIG. 1 is a front view of a display 10 in accordance with thepresent invention attached to media cassette 12 that permits a user toconveniently view time related information concerning a rental device.The time related information will include the return time for the mediacassette 12. Display 10 has a set of segments corresponding to the 7days of the week and the abbreviation AM and PM to indicate a time ofday. Display 10 is attached or fixed using adhesive to media cassette 12and can be electronically updated using contact pads 44. The display 10can also be formed as part of an article. Media cassette 12 is, forexample a rental unit that should be returned before the time shown ondisplay 10. When the display is attached to the article it can bereferred to as a label which has rewritable time related informationthat can be written, rewritten and viewed. It will be understood thatthe display 10, when functioning as a label, is associated with anarticle. For example, the display 10 can be attached to either thearticle which functions as a device to be used, such as media cassette12 or some rental device or a container which contains the mediacassette 12 or rental device or is associated with such a device.

[0031]FIG. 2 is a sectional view of display in FIG. 10. Display 10includes a flexible substrate 15, which is a thin transparent polymericmaterial, such as Kodak Estar film base formed of polyester plastic thathas a thickness of between 20 and 200 microns. In an exemplaryembodiment, substrate 15 can be a 125-micron thick sheet of polyesterfilm base. Other polymers, such as transparent polycarbonate can also beused.

[0032] First transparent conductor 20 is formed over substrate 15. Firsttransparent conductor 20 can be Tin-Oxide or Indium-Tin-Oxide (ITO),with ITO being the preferred material. Typically the ITO comprisingfirst transparent conductor 20 is sputtered as a layer over substrate 15to form a layer having a sheet resistance of less than 250 ohms persquare. The conductor 20 forms a part of each of the segments andtypically is grounded.

[0033] An optical state changing layer is formed by coating a lightmodulating layer 30 onto first conductor 20. In the preferredembodiment, light modulating layer 30 is a polymer dispersed cholestericliquid crystal. Cholesteric materials can be created that have peakreflectance from the infrared through the visible spectrum by varyingthe concentration of chiral dopant in a nematic liquid crystal.Application of electrical fields of various intensities and duration candrive a chiral nematic material (cholesteric) into a reflective state, atransmissive state or an intermediate state. These materials have theadvantage of maintaining a given state indefinitely after the field isremoved. Such materials can be cholesteric liquid crystal materials canbe Merck BL112, BL118 or BL126, available from EM Industries ofHawthorne, N.Y. Therefore in accordance with the invention, the material(which can be cholesteric liquid crystal) is effective in at least firstand second optical states so that the time related information can bewritten and viewed. The time related information relates to usage orpotential usage of the article or a device associated with the articleand such time related information can be electrically changed byproviding appropriate electrical fields to the material.

[0034] In an exemplary embodiment, light modulating layer 30 is acholesteric material dispersed in de-ionized photographic gelatin. Theliquid crystal material is dispersed at 8% concentration in a 5%de-ionized gelatin aqueous solution. It has been found that 10-microndiameter domains of the cholesteric liquid crystal in aqueous suspensionoptimize the electro-optical properties of the cholesteric materials.FIG. 3 is a sectional view through a polymer dispersed cholestericdomain showing that portions of incident light 54 at a given wavelengthwill become reflected light 56. The encapsulation process provides apressure resistant material that improves the viewing angle of thecholesteric liquid crystal. The first surface of light modulating layer30 is coated over first transparent conductor 20 to provide a 10-micronthick polymer dispersed cholesteric coating. Other organic binders suchas polyvinyl alcohol (PVA) or polyethylene oxide (PEO) can be used asthe polymeric agent. Such compounds are can be coated on equipmentassociated with photographic films.

[0035]FIG. 4 shows two stable states of cholesteric liquid crystals. Onthe left, a high planar voltage V2 been applied and quickly switched tozero potential, which applies and electric field that convertscholesteric liquid crystal to planar liquid crystal 50. Portions ofincident light 54 striking planar liquid crystal 50 becomes reflectedlight 56 to create a bright image. On the right, application of a lowerfocal-conic voltage V1 applies an electric field that convertscholesteric liquid crystal to transparent focal-conic liquid crystal 52.Incident light 54 striking focal-conic liquid crystal 52 is transmitted.A light absorber 58 will absorb incident light 54 to create a dark imagein areas having focal-conic liquid crystal 52. As a result, a viewerperceives an image having bright and dark areas depending on if thecholesteric material is planar liquid crystal 50 or focal-conic liquidcrystal 52, respectively. A display 10 having light modulating layer 30needs to have one transparent conductor and one light absorbingconductor. In the first exemplary embodiment, first transparentconductor 20 is transparent ITO.

[0036] For the exemplary embodiment, assume the display 10 requires 10volts per micron thickness to convert the cholesteric material into theplanar state. For an 8 micron layer, planar voltage V2 should be an 80volt pulse for approximately 20 milliseconds converts cholesteric liquidcrystals into the planar state. A pulse of about half the fieldstrength, or 5 volts per micron converts the liquid crystal to thefocal-conic state. If field carrying electrodes are spaced apart by adielectric layer, then the field strength is reduced.

[0037] Returning to FIG. 2, a dielectric layer 40 is screen printed overlight modulating layer 30. Dielectric layer 40 can be a 25 micron thicklayer of Electrodag 25208 screen printable, UV curable dielectriccoating from Acheson Corporation. The material is thermoplastic that isscreen printable and hardens exposed to 0.3-0.6 joules/cm² of ultraviolet radiation. A dielectric layer 40 screen printed at 25 micronsthickness reduces the field strength to reduce planar pulse to less thanthe 5 volts per micron focal-conic field strength. Openings 41 indielectric layer 40 to define image areas, which are coincident with theopenings 41. Since the image is viewed through substrate 15, the indiciaare mirror-imaged.

[0038] Second conductors 42 are then printed over dielectric layer 40.Second conductors 42 can be formed of a 25 micron thick layer ofElectrodag 423SS screen printable electrical conductive material fromAcheson Corporation. The material is finely divided graphite particlesin a thermoplastic resin. The effective sheet conductivity of a 25micron printed layer is than 250 ohms per square. Such a layer is lightabsorbing, typically having an optical density of greater than 2.0 D.The light absorbing property of the second conductor 42 is adequate toserve as light absorber 58 for the cholesteric liquid crystal material.

[0039] In each of the image areas under openings 41, second conductor 42directly contacts light modulating layer 30. A planar voltage V2 appliedbetween first transparent conductor 20 and second conductor 42 in animage area will have a 10 volts per micron field strength and convertcholesteric liquid crystals in light modulating layer 30 to planarliquid crystals 50. Areas having a 25 micron thick dielectric layer 40will only experience 2.8 volts per micron and cannot be switched to theplanar state if a 100 volt pulse is applied between first transparentconductor 20 and second conductor 42. The display 10 is arranged so thatdisplay 10 can be viewed only through the transparent substrate. Anadhesive 46 is applied to the back of the label, which bonds display 10to media cassette 12.

[0040] The process for manufacturing displays 10 is shown in FIGS.5A-5F. FIG. 5A is a rear view of a substrate 15 supporting firsttransparent conductor 20 and light modulating layer 30. FIG. 5B is thestructure from FIG. 5A after removal of a portion of light modulatinglayer 30 to reveal first transparent conductor 20. In the case of agelatin and liquid crystal emulsion, light modulating layer 30 isremoved by immersion in water and mechanical agitation. FIG. 5C is thestructure of FIG. 5B after being printed with dielectric layer 40 havingopenings 41 defining image areas. Openings 41 in dielectric layer 40expose areas of first transparent conductor 20.

[0041]FIG. 5D is the structure of FIG. 5C having a second conductor 42printed over each indicia of display 10. Through holes 43 are perforatedthrough the entire structure outside of the indicia but through eachsecond conductor 42. FIG. 5E is the display 10 of FIG. 5D, afterapplication of thin, metallic contact pads 44. Contact pads 44 can be 25micron gold plated copper sheets having a conductive adhesive that bondseach contact pad 44 over each through hole 43. FIG. 5F is the display 10of FIG. 5E further including an adhesive 46, such as a contact adhesive,coated over the display 10. The completed display 10 of FIG. 5F can beattached to an A/V cassette. The top nine contacts of the displaycorrespond to the 7 days of the week and the morning and eveningportions of each day. The bottom contact pad 44 provides an electricalground to first transparent conductor 20.

[0042]FIG. 6A is a sectional view of display 10 showing electricalinterconnect detail for the indicia. Contact 60 passes through hole 43and engages contact pad 44. A contact pad 44 is bonded to each secondconductor 42 for each indicia. FIG. 6B is a sectional view of theelectrical interconnection to first transparent conductor 20. Contact 60passes through hole 43 to connect with contact pad 44. Becausedielectric layer 40 is not printed in the area and light modulatinglayer 30 has been removed, contact pad 42 is connected to firsttransparent conductor 20 to provide a ground field under each indicia.

[0043]FIG. 7 is an electrical schematic of the circuitry used to writedisplay 10. Contacts 60 pass through holes 43 to engage contact pads 44as shown in FIGS. 6A and 6B. In FIG. 7, contact is made to the rightmost segment and connects first transparent conductor 20 to ground. Theother segments are electrically connected to display drive 66. Powersupply 62 generates two voltages, a first planar driving voltage and asecond focal-conic voltage. A voltage select circuit 64 is used toselect one of the two voltages. Voltage select circuit 64 can be assimple as a resistor network and a switching transistor. Control signalsare applied to the voltage select circuit 64 and also to display drive66. Display drive 66 is used to apply the selected voltage toappropriate segments of the display 10. In this way, the circuitryselectively addresses the different segment to cause them to be in anappropriate optical state for viewing or rewriting. Display drive 66operates on a selected voltage from voltage selector 64 and applieseither a ground or selected voltage to contacts 60. Display drive 66 canfor example be embodied in a commercially available device known asHV57908PG from Supertex, Inc. of Sunnyvale, Calif.

[0044]FIG. 8 is a diagram of the voltage waveform applied by displaydrive 66 to drive display 10. Voltage select circuit 64 is first set tothe lower, focal-conic voltage V1 and all contacts 60 connected tosecond conductor 42 are receive a pulse of focal-conic voltage V1 toclear any reflective image from display 10. Voltage select circuit 64 isthen set to apply a higher planar voltage V2 to display drive 66.Display drive 66 is then switched to apply planar voltage V2 acrossselected segments that are to be placed in the reflective, planar state.Those segments that are to remain non-reflective are not switched. Thewaveform shows the sequence of voltages that are used to write indiciainto the planar state. Planar voltage V2 is omitted to maintain indiciain the clear focal-conic state. The drive method is a simple method oferasing and re-writing display 10.

[0045] The invention discloses an arrangement to use re-writableattachable time labels for rental devices such as audio-visual recordingcassettes. The invention has been described in detail with particularreference to certain preferred embodiments thereof, but it will beunderstood that variations and modifications can be effected within thespirit and scope of the invention. PARTS LIST 10 display 12 mediacassette 15 substrate 20 first transparent conductor 30 light modulatinglayer 40 dielectric layer 41 openings 42 second conductors 43 throughholes 44 contact pads 46 adhesive 50 planar liquid crystals 52focal-conic liquid crystals 54 incident light 56 reflected light 58light absorber 60 contacts 62 power supply 64 voltage select circuit 66display drive

What is claimed is:
 1. A method of recording rewritable time relatedinformation on a label which can be provided on an article, comprisingthe steps of: a) providing an electrically rewritable label whichincludes a plurality of rewritable segments, each such segment having alayer including a material which is effective in at least first andsecond optical states so that the time related information can bewritten, rewritten and viewed, wherein such time related informationrelates to usage or potential usage of the article or a deviceassociated with the article and such time related information can beelectrically changed by providing appropriate electrical fields to thematerial; b) providing the label to be associated with the article; andc) electrically addressing selected segments to write or rewriteappropriate time related information.
 2. A method of recordingrewritable time related information on a label which can be provided onan article, comprising the steps of: a) providing an electricallyrewritable label which includes a plurality of rewritable segments, eachsuch segment having a layer including cholesteric liquid crystalmaterial which is effective in at least first and second optical statesso that the time related information can be written, rewritten andviewed, wherein such time related information relates to usage orpotential usage of the article and such time related information can beelectrically changed by providing appropriate electrical fields to thematerial; b) providing the label to be associated with the article; andc) electrically addressing selected segments to write or rewriteappropriate time related information.
 3. A method of recordingrewritable time related information on a label which can be provided ona rental article, comprising the steps of: a) providing an electricallyrewritable label which includes a plurality of rewritable segments, eachsuch segment having a layer of a material which is effective in at leastfirst and second optical states so that the return time relatedinformation can be written and viewed, wherein such return time relatedinformation relates to usage or potential usage of the article and suchreturn time related information can be electrically changed by providingappropriate electrical fields to the material; b) providing the label tobe associated with the article; and c) electrically addressing selectedsegments to write or rewrite appropriate time related information. 4.The method of claim 3 wherein the material includes cholesteric liquidcrystal.
 5. The method of claim 3 wherein the rental article is a mediacassette.
 6. A method of recording rewritable time related informationon a label which can be provided on a rental article, comprising thesteps of: a) providing an electrically rewritable label which includes aplurality of rewritable segments, each such segment having a transparentsubstrate, a transparent electrode over such substrate, a layerincluding cholesteric liquid crystal material, a dielectric layer havingopenings, and a second conductor provided over the dielectric layer andinto the openings to be in contact with the cholesteric liquid crystalbearing layer and which is effective at the position in such openings tobe in at least first and second optical states so that the return timerelated information can be written and viewed, wherein such return timerelated information relates to usage or potential usage of the articleand such return time related information can be electrically changed byproviding appropriate electrical fields to the material; b) providingthe label to be associated with the article; and c) electricallyaddressing selected segments to erase undesired previous return timerelated information and writing appropriate return time relatedinformation.